This invention relates generally to a bipolar electrosurgical device, such as a trocar, for penetrating tissue.
Tissue penetrating probes, such as trocars and insufflation needles, are well known. A trocar typically includes an elongate stylet having a sharp, pointed obturator tip, disposed within a sheath or sleeve, and a handle portion that controls reciprocation of the stylet. A user of the trocar grips the handle and applies force such that the sharp tip of stylet penetrates tissue to a desired depth. A common use of the trocar is to gain access to the abdominal cavity for subsequent surgical purposes. This is typically accomplished by penetrating the abdomen with the tip of the stylet, removing the stylet from the sheath, and leaving the sheath within the abdominal wall to serve as a conduit to facilitate surgical procedures or inspections.
Insufflation needles are known devices, smaller in diameter than trocars, that also enable penetration of the abdominal wall. These often are used to insufflate the abdominal cavity before a larger opening is made with a trocar.
Electrosurgical energy, typically in the radio frequency range, has been used to enhance surgical procedures. Surgical tools utilizing electrosurgical energy are disclosed in U.S. patent application Ser. No. 786,572, filed on Nov. 1, 1991, and U.S. patent application Ser. No. 005,600, filed on Jan. 19, 1993.
Various monopolar electrosurgical devices also are known. However, monopolar devices are not believed to be the most effective means for applying electrosurgical energy in surgical techniques. Typically, a remote ground pad is placed on the patient to form the negative pole in the electrosurgical circuit. The energy applied through the electrosurgical instrument must often traverse significant distances through the patient's body before reaching the return electrode. This can lead to ineffective control in applying the optimal mount of energy. In some instances patient burning can also result due to poor contact of the ground pad or ineffective control of energy delivery.
A trocar that uses electrosurgical energy is described in International Application No. WO/92/14514. The trocar can be monopolar or bipolar. In the monopolar mode the obturator tip of the trocar serves as the active electrode while a remote ground pad serves as the return electrode. In the bipolar mode the obturator tip has two separate, insulted elements (foraging a "duckbill" shape), each of which serves as one of the poles. Although this form of the trocar is bipolar in the sense that it forms both poles in circuit, it does so on the single cutting element and does not simultaneously function as a traditional trocar.
Despite existing technology applied to electrosurgical trocars, there remains a need for an effective bipolar trocar able to safely utilize electrosurgical energy to assist in penetrating and cauterizing tissue.
Accordingly, an object of the invention is to provide a bipolar tissue penetrating probe that uses electrosurgical energy to enhance tissue penetration and to cauterize tissue simultaneous with tissue penetration. Another object is to provide a bipolar trocar device able to penetrate and to cauterize tissue simultaneously. A further object of the invention is to provide such a device that enables more effective use of electrosurgical energy to penetrate and cauterize tissue. These and other objects of the invention will be evident from the disclosure that follows.